MHTCET 23 Apr 2025 Shift 1 Paper

Concept:The nature of a salt solution depends on the strength of the acid and base from which the salt is formed.Explanation:$\mathrm{NH}_{4}\mathrm{NO}_{3}$ comes from a weak base ($\mathrm{NH}_{4}\mathrm{OH}$) and a strong acid ($\mathrm{HNO}_{3}$).Its aqueous solution is acidic because $\mathrm{NH}_{4}^{+}$ undergoes hydrolysis to produce $\mathrm{H}^{+}$ ions.So, it is not basic.$\mathrm{NH}_{4}\mathrm{Cl}$ is formed from a weak base ($\mathrm{NH}_{4}\mathrm{OH}$) and a strong acid ($\mathrm{HCl}$).It also gives an acidic solution due to $\mathrm{NH}_{4}^{+}$ hydrolysis.So, it is not basic.$\mathrm{Na}_{2}\mathrm{CO}_{3}$ is formed from a strong base ($\mathrm{NaOH}$) and a weak acid ($\mathrm{H}_{2}\mathrm{CO}_{3}$).In water, the carbonate ion hydrolyzes as follows:$$\mathrm{CO}_{3}^{2-} + \mathrm{H}_{2}\mathrm{O} \rightleftharpoons \mathrm{HCO}_{3}^{-} + \mathrm{OH}^{-}$$This produces $\mathrm{OH}^{-}$ ions, making the solution basic.Hence, $\mathrm{Na}_{2}\mathrm{CO}_{3}$ is the correct choice.$\mathrm{Na}_{2}\mathrm{SO}_{4}$ is formed from a strong base ($\mathrm{NaOH}$) and a strong acid ($\mathrm{H}_{2}\mathrm{SO}_{4}$).It does not hydrolyze significantly, so its solution is neutral.Answer:Option C: $\mathrm{Na}_{2}\mathrm{CO}_{3}$ forms a basic solution in water.